| Abstract
| - A short synthesis of (±)-deoxypenostatin A (28) has been carried out using the convergent couplingof dienal 11, epoxide 13, and methylenetriphenylphosphorane (17) to prepare trienol 19 in onlytwo steps. The key step is the Yb(OTf)3-catalyzed intramolecular Diels−Alder reaction of hydratedtrienyl glyoxylate 23, which gives lactone 24 stereoselectively. Elaboration of lactone 24 to enone27 by an intramolecular Horner−Emmons Wittig reaction and epimerization completes the synthesisof 28. Modest yields of Diels−Alder adducts 45a and 46a could be prepared analogously from MEMether 44c, but the sensitivity of several of the intermediates precluded the elaboration of 45a topenostatin A (1).
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